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Scientists scramble to expand sites to test mosquitoes for West Nile virus

Scientists in western Washington are quickly trying to expand the number of sites that collect mosquitoes to test for West Nile virus.

The Washington State Department of Health (DOH) confirmed discovery of the virus in Tacoma mosquitoes on Tuesday – it’s the first time West Nile has shown up in mosquitoes west of the Cascades.

KIRO7's Deedee Sun found out most counties in western Washington do not monitor mosquitoes for the virus -- and the state doesn't have the money to take over all the work it says needs to be done.

The DOH spent Wednesday scouting out new sites for traps for mosquitoes and found some new options in Tacoma metro parks. (The DOH doesn’t want to specify which parks so the traps don’t get disturbed.)

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Biologist David Kangiser with the DOH showed KIRO7 a trap collected from Thurston County full of mosquitoes.

“There are 80 to 100 in here, which is typical,” Kangiser said.

After 16 years of surveillance in Pierce and Thurston counties, it’s the first time the DOH found West Nile-positive mosquitoes.

“My initial reaction was, wow. Holy cow,” Kangiser said.

The traps the DOH set use dry ice -- or carbon dioxide.

“That’s what mosquitoes are attracted to,” Kangiser said. “It’s what we exhale.”

The traps are hung up in the evening, collect mosquitoes overnight, and are retrieved in the morning.

Right now there's only one trap in Pierce County and three in Thurston County.

“Does this mean the amount of testing that happens in western Washington needs to expand?” KIRO7’s Deedee Sun asked.

“Absolutely. Just because we found it in one place doesn't mean it's not in more places. We only know it's in one place because that's where we found it,” Kangiser said.

Kangiser said the DOH is adding four more traps in Pierce County this week.

But one big problem -- the state’s program to monitor mosquitoes is made up of just six people. And Kangiser says most local jurisdictions in western Washington don't have the resources to help.

“A lot of the funding at the local level has been cut over the years,” he said. “They just don't have the resources to keep up, so yeah it falls on us. Our crew of six,” he said.

He says their team already process a half-million mosquitoes a year. There are 52 species of mosquitoes in Washington but only two species can transmit West Nile, so each mosquito has to be sorted by hand.

“It’s an enormous work load. There are times we definitely feel overwhelmed,” Kangiser said.

Researchers at the University of Washington have some thoughts on why West Nile is showing up for the first time so far west.

Dr. Cory Morin tracks mosquitoes and disease and says western Washington's longer and warmer summers could be playing a role.

“It’s possibly the seasonality is changing, so that the mosquitoes can last for a longer period of time before it gets too cold for them to survive,” Morin said.

That gives mosquitoes more time to get infected, for the virus to develop within the mosquito, and more means more favorable conditions for disease.

“For certain pathogens, they replicate faster at warmer temperatures, so when you have warmer temperatures, you have faster replication of the bacteria. This is true for things like West Nile virus but also other diseases,” Morin said.

People enjoying nature in Tacoma call it a shame that now West Nile is something western Washington needs to worry about.

“I'm pretty shocked,” said Emily Barker said. She was running through a Tacoma park that will get a mosquito test trap next week.

“Going through the wet parts with the turtles and ducks, that's the best part. You don't want to run out by giant disease-carrying mosquitoes,” she said.

The DOH is now working to figure out exactly how widespread the virus is -- but right now, there are no traps or monitoring King County, Snohomish County - or most counties in western Washington.

“There are huge surveillance gaps we really need to address,” Kangiser said. The DOH will add traps to more counties for mosquito testing next season.

For now, the state says it is training people with the Pierce County Health Department to help collect mosquitoes and will ask the state Legislature, for more funding.

Kangiser also says there is a silver lining.

“The fact that we found it in the mosquitoes before we found it in human cases in the state is a great scenario. So now we can have an early warning system, get it out to the public -- hey, protect yourself,” he said.

Tips include wearing long sleeves and pants, and using an insect repellent with DEET. DOH also recommends checking the area around your home for any standing water, like in gutters and bird baths.

More tips from the CDC here: https://www.cdc.gov/westnile/prevention/index.html 

As for West Nile symptoms, the CDC says:

No symptoms in most people. Most people  (eight out of 10) infected with West Nile virus do not develop any symptoms.

Febrile illness (fever) in some people. About 1 in 5 people who are infected develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.

Serious symptoms in a few people. About 1 in 150 people who are infected develop a severe illness affecting the central nervous system such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord).